Metabolites in safety testing assessment in early clinical development: a case study with a glucokinase activator

• Published in: Drug metabolism and disposition Vol. 42; no. 11; pp. 1926 - 1939
• Main Authors: Sharma, Raman, Litchfield, John, Atkinson, Karen, Eng, Heather, Amin, Neeta B, Denney, William S, Pettersen, John C, Goosen, Theunis C, Di, Li, Lee, Esther, Pfefferkorn, Jeffrey A, Dalvie, Deepak K, Kalgutkar, Amit S
• Format: Journal Article
• Language: English
• Published: United States 01.11.2014
• Subjects: Animals; Area Under Curve; Benzofurans - blood; Benzofurans - pharmacokinetics; Dogs; Enzyme Activators - blood; Enzyme Activators - pharmacokinetics; Female; Glucokinase - metabolism; Humans; Pyrimidines - blood; Pyrimidines - pharmacokinetics; Rats
• ISSN: 0090-9556; 1521-009X
• DOI: 10.1124/dmd.114.060087

The present article summarizes Metabolites in Safety Testing (MIST) studies on a glucokinase activator, N,N-dimethyl-5-((2-methyl-6-((5-methylpyrazin-2-yl)carbamoyl)benzofuran-4-yl)oxy)pyrimidine-2-carboxamide (PF-04937319), which is under development for the treatment of type 2 diametes mellitus. Metabolic profiling in rat, dog, and human hepatocytes revealed that PF-04937319 is metabolized via oxidative (major) and hydrolytic pathways (minor). N-Demethylation to metabolite M1 [N-methyl-5-((2-methyl-6-((5-methylpyrazin-2-yl)carbamoyl)benzofuran-4-yl)oxy)pyrimidine-2-carboxamide] was the major metabolic fate of PF-04937319 in human (but not rat or dog) hepatocytes, and was catalyzed by CYP3A and CYP2C isoforms. Qualitative examination of circulating metabolites in humans at the 100- and 300-mg doses from a 14-day multiple dose study revealed unchanged parent drug and M1 as principal components. Because M1 accounted for 65% of the drug-related material at steady state, an authentic standard was synthesized and used for comparison of steady-state exposures in humans and the 3-month safety studies in rats and dogs at the no-observed-adverse-effect level. Although circulating levels of M1 were very low in beagle dogs and female rats, adequate coverage was obtained in terms of total maximal plasma concentration (∼7.7× and 1.8×) and area under the plasma concentration-time curve (AUC; 3.6× and 0.8× AUC) relative to the 100- and 300-mg doses, respectively, in male rats. Examination of primary pharmacology revealed M1 was less potent as a glucokinase activator than the parent drug (compound PF-04937319: EC50 = 0.17 μM; M1: EC50 = 4.69 μM). Furthermore, M1 did not inhibit major human P450 enzymes (IC50 > 30 μM), and was negative in the Salmonella Ames assay, with minimal off-target pharmacology, based on CEREP broad ligand profiling. Insights gained from this analysis should lead to a more efficient and focused development plan for fulfilling MIST requirements with PF-04937319.